"Guardian" (ガーディアン Gādian) is an archetype of monsters used by Rafael in the second series anime. The original "Guardian" monsters each have a corresponding Equip Spell Card. Regardless, the archetype's support card works with all monsters with "ガーディアン" in their Japanese names. Its English lore does exclude some monsters with "Guardian" in their names, but the reason for that is that those cards do not have "ガーディアン" in their Japanese names.
The core "Guardian" monsters were initially released in Dark Crisis and re-released in Dark Revelation Volume 1. They can only be Summoned if that Equip Card is already face-up on the field. However you can still Set them since it's only Normal and Special Summons that you cannot do unless the Equip Card is face-up on the field.
The Equip Spell does not have to be equipped to their corresponding monster and due to their Summoning conditions, usually can't be. The only "Guardian" that is an exception to this rule is "Guardian Eatos", who can be Special and Normal Summoned without restrictions.
|Equip Spell Card||Guardian|
|Rod of Silence||Kay'est|
|Shooting Star Bow||Ceal|
|Twin Swords of Flashing Light||Tryce|